Fuse devices and methods of operating the same

ABSTRACT

A fuse device includes a fuse unit, which includes a cathode, an anode, and a fuse link coupling the cathode and the anode. A transistor includes at least a portion of the fuse unit to be used as an element of the transistor.

PRIORITY STATEMENT

This application is a divisional of and claims priority under 35 U.S.C.§120/121 on application Ser. No. 12/285,914, filed on Oct. 16, 2008,which claims priority under 35 U.S.C. §119 to Korean Patent ApplicationNo. 10-2008-0022608, filed on Mar. 11, 2008, in the Korean IntellectualProperty Office, the entire contents of each of which are incorporatedherein by reference.

BACKGROUND

A conventional fuse device may be used in semiconductor memory devicesor logic devices for various purposes, such as repairing defectivecells, chip identification (ID) information, circuit customization, etc.For example, cells determined as defective can be replaced withredundancy cells by a fuse device. Accordingly, a decrease in amanufacturing yield due to the defective cells can be resolved.

Two types of fuse devices are a laser-blown type and anelectrically-blown type. The laser-blown type fuse device may use alaser beam to blow a fuse line.

On the other hand, the electrically-blown type fuse device may apply aprogramming current to a fuse link so that the fuse link is blown due toan electromigration (EM) effect and a Joule heating effect. The methodof electrically blowing a fuse can be used after packaging asemiconductor chip. A fuse device employing the method of electricallyblowing a fuse may be referred to as an electrical fuse device.

A conventional electrical fuse device may have a change in electricalresistance caused by blowing the fuse link. However, according to theconventional method, a sufficient sensing margin cannot be obtained, andthus it may be difficult to reduce the sizes of a fuse device and asemiconductor device including the fuse device.

SUMMARY

Example embodiments relate to fuse devices and methods of operating andmanufacturing the same. Fuse devices according to example embodimentsmay include a fuse link.

Example embodiments provide a fuse device which may include a fuse unithaving a cathode, an anode, and a fuse link coupling the cathode and theanode, and a transistor in which at least a portion of the fuse unit maybe used as an element of the transistor.

According to at least some example embodiments, the transistor mayinclude a source and a drain disposed on a substrate at each of twosides of the fuse link, and the transistor may use the fuse link as agate. At least one of the source and the drain may have a fuse structureincluding two regions located apart from each other, and a link regionwhich may have a width less than each of the two regions and may belocated between the two regions.

Example embodiments provide that the transistor may use the fuse unit asa source. The transistor may further include a drain located apart fromthe source and a gate disposed on a substrate between the source and thedrain.

According to another example embodiment, the transistor may use the fuseunit as a drain. Furthermore, the transistor may include a sourcelocated apart from the drain and a gate disposed on a substrate betweenthe source and the drain.

In accordance with at least some example embodiments, the fuse link mayinclude a conductive layer and a highly-resistant region in a portion ofthe conductive layer, wherein the highly-resistant region may be aregion having an electrical resistance higher than that of a remainingportion of the conductive layer. The highly-resistant region may becloser to the cathode than to the anode. The highly-resistant region maybe a silicon region, and the remaining portion of the conductive layermay be a silicide region. The conductive layer may be a metal layer, andthe highly-resistant region may be a doped region.

In accordance with another example embodiment, a transistor may use afuse link as a gate and at least one of a source and a drain includes afuse structure. A link region in the source and the drain may include ahighly-resistant region.

Another example embodiment provides a method of operating a fuse deviceincluding a fuse unit, which includes a cathode, an anode, a fuse unit,and a fuse link coupling the cathode and the anode, and a transistor inwhich at least a portion of the fuse is used as an element of thetransistor. The method may include applying a programming current to thefuse unit and measuring a drain current of the transistor.

According to another example embodiment, a transistor may include asource and a drain disposed on a substrate at each of two sides of thefuse link, and the transistor may use the fuse link as a gate. A gatevoltage may be supplied to the cathode or the anode and a voltage may besupplied between the source and the drain to measure the drain current.

In at least one example embodiment wherein the transistor uses the fuselink as a gate, at least one of the source and the drain may include afuse structure including two regions located apart from each other and alink region which has a width less than that of each of the two regionsand is located between the two regions. The method may further includeapplying another programming current to at least one of the source andthe drain having the fuse structure, prior to measuring the draincurrent.

According to some example embodiments, a transistor may use the fuseunit as a source and may include a drain located apart from the sourceand a gate disposed on a substrate between the source and the drain. Agate voltage may be supplied to the gate and a voltage may be suppliedbetween the cathode and the drain to measure the drain current.

At least another example embodiment provides that a transistor may usethe fuse unit as a drain and may include a source located apart from thedrain and a gate disposed on a substrate between the source and thedrain. A gate voltage may be supplied to the gate and a voltage may besupplied between the cathode and the source to measure the draincurrent.

According to at least some example embodiments, a portion of the fuselink may be blown due to a programming current. If the transistor usesthe fuse link as a gate and at least one of the source and the drain hasthe fuse structure, the link regions of the source and/or the drain maybe blown by another programming current.

At least some example embodiments provide that, a fuse link may includea conductive layer and a highly-resistant region in a portion of theconductive layer, wherein the highly-resistant region is a region havingan electrical resistance higher than that of a remaining portion of theconductive layer. The highly-resistant region may move into the cathodedue to a programming current.

In accordance with another example embodiment, a transistor may use thefuse link as a gate and at least one of the source and the drain has thefuse structure. The link region in the source and the drain may includeanother highly-resistant region. The other highly-resistant region maybe moved out of the link region due to the other programming current.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A is a plan view of a fuse device according to an exampleembodiment before the fuse device may be programmed;

FIG. 1B is a cross-sectional view obtained along a line I-I′ of FIG. 1A;

FIG. 2A is a plan view of the fuse device of FIG. 1A after the fusedevice may be programmed;

FIG. 2B is a cross-sectional view obtained along a line I-I′ of FIG. 2A;

FIG. 3A is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed;

FIG. 3B is a cross-sectional view obtained along a line II-II′ of FIG.3A;

FIG. 4A is a plan view of the fuse device of FIG. 3A after the fusedevice may be programmed;

FIG. 4B is a cross-sectional view obtained along a line II-II′ of FIG.4A;

FIG. 5 is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed;

FIG. 6 is a plan view of the fuse device of FIG. 5 after the fuse devicemay be programmed;

FIG. 7A is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed;

FIG. 7B is a cross-sectional view obtained along a line III-III′ of FIG.7A;

FIG. 8A is a plan view of the fuse device of FIG. 7A after the fusedevice may be programmed;

FIG. 8B is a cross-sectional view obtained along a line III-III′ of FIG.8A;

FIG. 9A is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed;

FIG. 9B is a cross-sectional view obtained along a line IV-IV′ of FIG.9A;

FIG. 10A is a plan view of the fuse device of FIG. 9A after the fusedevice may be programmed;

FIG. 10B is a cross-sectional view obtained along a line IV-IV′ of FIG.10A;

FIG. 11 is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed;

FIG. 12 is a plan view of the fuse device of FIG. 11 after the fusedevice may be programmed;

FIGS. 13A through 13C are cross-sectional views showing a method ofmanufacturing a fuse device, according to an example embodiment; and

FIGS. 14A through 14C are cross-sectional views showing a method ofmanufacturing a fuse device, according to another example embodiment.

DETAILED DESCRIPTION

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare shown. In the drawings, the thicknesses of layers and regions areexaggerated for clarity.

Detailed illustrative example embodiments are disclosed herein. However,specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Thisinvention may, however, may be embodied in many alternate forms andshould not be construed as limited to only the example embodiments setforth herein.

Accordingly, while example embodiments are capable of variousmodifications and alternative forms, embodiments thereof are shown byway of example in the drawings and will herein be described in detail.It should be understood, however, that there is no intent to limitexample embodiments to the particular forms disclosed, but on thecontrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope of the invention.Like numbers refer to like elements throughout the description of thefigures.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and/or,” includes any and all combinations of oneor more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments of the invention.

It will be understood that when an element is referred to as being“connected,” or “coupled,” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected,” or “directly coupled,” to another element, there are nointervening elements present.

It will be understood that when an element or layer is referred to asbeing “formed on,” another element or layer, it can be directly orindirectly formed on the other element or layer. That is, for example,intervening elements or layers may be present. In contrast, when anelement or layer is referred to as being “directly formed on,” toanother element, there are no intervening elements or layers present.Other words used to describe the relationship between elements or layersshould be interpreted in a like fashion (e.g., “between,” versus“directly between,” “adjacent,” versus “directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an,” and “the,”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises,” “comprising,” “includes,” and/or “including,” whenused herein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Fuse devices and methods of operating and manufacturing the sameaccording to example embodiments will now be described more fully withreference to the accompanying drawings.

FIG. 1A is a plan view of a fuse device according to an exampleembodiment before the fuse device may be programmed, and FIG. 1B is across-sectional view of the fuse device obtained along a line I-I′ ofFIG. 1A.

Referring to FIG. 1A, the electrical fuse device may include a cathode100 and an anode 200 that are located apart from each other, and a fuselink 150 that is disposed between the cathode 100 and the anode 200 soas to link the cathode 100 and the anode 200. The cathode 100, the anode200, and the fuse link 150 may form a fuse unit F1, and a sidewallinsulation layer 10 covering sidewalls of the fuse unit F1 may furtherbe provided. Shapes of the cathode 100 and the anode 200 may berectangles, and a width W1 of the cathode 100 may be larger than a widthW2 of the anode 200. The shapes of the cathode 100 and the anode 200 canvary, and their sizes and size ratio can also vary. The fuse link 150may have a width significantly smaller than that of the cathode 100 andthe anode 200. For example, the fuse link 150 may have a width betweendozens of nanometers (nm) to hundreds of nm and a length between dozensof nm and several micrometers (μm). When a current exceeding a criticalpoint flows through the fuse link 150, a particular region of the fuselink 150 may be blown due to an electromigration (EM) effect and a Jouleheating effect. As the width of the fuse link 150 decreases and thelength of the fuse link 150 increases, the fuse link 150 can be blownmore easily.

First and second conductive regions 300 a and 300 b may be disposed ateach of two sides of the fuse link 150, respectively. One of the firstand second conductive regions 300 a and 300 b may be a source, and theother may be a drain. The fuse link 150 between the first and secondconductive regions 300 a and 300 b may be a gate. In other words, thefuse link 150 and the first and second conductive regions 300 a and 300b may form a switching device such as a transistor T1.

Referring to FIG. 1B, the fuse link 150 may include an insulation layer150 a and a conductive layer 150 b, which are formed on a substrate 1 insequence, and the conductive layer 150 b may have a multi-layerstructure. The insulation layer 150 a and the conductive layer 150 b maybe referred to as a gate insulation layer and a gate conductive layer,respectively. The conductive layer 150 b may be a stacked layerstructure including a lower layer L1 and an upper layer L2 disposed onthe lower layer L1. Although the lower layer L1 may be a poly-siliconlayer and the upper layer L2 may be a silicide layer, the exampleembodiments are not limited thereto, and thus, the structure andmaterial of the conductive layer 150 b may vary. For example, theconductive layer 150 b may have either a single metal layer structure ora multi-metal layer structure. If the conductive layer 150 b has abi-metal layer structure, the lower layer L1 may be formed of one of Ti,TiN, and TaN, for example, and the upper layer L2 may be formed of oneof W, Al, and Cu, for example. The list is not exhaustive. The cathode100 and the anode 200, shown in FIG. 1A, may have the same stacked layerstructure as the fuse link 150 shown in FIG. 1B.

Meanwhile, the first and second conductive regions 300 a and 300 b mayinclude first and second doped regions 300 a′ and 300 b′, which aredisposed in the substrate 1 at both sides of the fuse link 150 and aredensely doped with conductive impurities. Also, the first and secondconductive regions 300 a and 300 b may further include first and secondcontact layer regions 300 a″ and 300 b″, which are formed on the topsurfaces of the first and second doped regions 300 a′ and 300 b′. Thefirst and second contact layer regions 300 a″ and 300 b″ may be regionsfor lowering contact resistance. The first and second contact layerregions 300 a″ and 300 b″ may be a silicide region, for example, but thematerial forming the first and second contact layer regions 300 a″ and300 b″ may vary. The formation of the first and second contact layerregions 300 a″ and 300 b″ may be optional.

Although not shown in FIGS. 1A and 1B, the cathode 100 and the anode 200may be coupled to a sense circuit and a programming transistor. Sincethe sense circuit and the programming transistor are well known to thoseof ordinary skill in the art, further descriptions thereof will not beprovided.

The fuse device shown in FIG. 1A may be changed as shown in FIG. 2A by aprogramming operation. In other words, FIG. 1A shows the fuse devicebefore the fuse device may be programmed, and FIG. 2A shows the fusedevice after the fuse device may be programmed. FIG. 2B is across-sectional view of the fuse device obtained along a line I-I′ ofFIG. 2A.

Referring to FIGS. 2A and 2B, electrons may move from the cathode 100 tothe anode 200 due to a programming current applied from the anode 200 tothe cathode 100. The electrons cause an electromigration effect and aJoule heating effect in the upper layer L2 (FIG. 1B) of the fuse link150, and thus a certain region of the upper layer L2 may be blown. InFIGS. 2A and 2B, a reference character B1 may indicate the blown region.Accordingly, as the fuse link 150 is blown, a drain current of thetransistor T1 may change. The drain current can be measured by applyinga voltage between the first and second conductive regions 300 a and 300b (that is, applying a source voltage Vs to one of the first and secondconductive regions 300 a and 300 b, and applying a drain voltage Vd tothe other), and supplying a gate voltage Vg to the fuse link 150 viaeither the cathode 100 or the anode 200. The drain current of thetransistor T1 when the fuse link 150 is not blown and the drain currentof the transistor T1 when the fuse link 150 is blown may be different.Thus, the difference between the drain currents can be measured easily.More specifically, a valid gate voltage may decrease when the fuse link150 is blown as compared to when the fuse link 150 is not blown, andthus, generating a channel in the substrate 1 between the first andsecond conductive regions 300 a and 300 b becomes difficult. As aresult, the drain current may decrease significantly.

Although a conventional fuse device may use a change in the electricalresistance of the fuse itself caused by blowing the fuse, fuse devicesaccording to example embodiments may use a change in the drain currentof the transistor T1 in which portion of the fuse unit F1 is used as anelement of the transistor T1. A changing margin of the drain current isfar larger than a changing margin of the current due to the change inelectrical resistance of the conventional fuse unit, and thus a largesensing margin can be obtained according to example embodiments. As thesensing margin becomes larger, configuration of a sense circuit (notshown) coupled to the transistor T1 and/or the fuse unit F1 can becomesimpler. As a result, the size of a unitary fuse device can be reduced.

FIG. 3A is a plan view of a fuse device according to another exampleembodiment before the fuse device may be programmed, and FIG. 3B is across-sectional view of the fuse device obtained along a line II-II′ ofFIG. 3A.

Referring to FIG. 3A, the fuse device may include a fuse unit F2 havinga planar structure similar to that of the fuse unit F1 shown in FIG. 1A.The fuse unit F2 may include a cathode 100′ and an anode 200′ locatedapart from each other and a fuse link 150′ coupling the cathode 100′ andthe anode 200′. The fuse device may include a third conductive region300 c, located apart from the fuse unit F2, and a gate 400 between thefuse unit F2 and the third conductive region 300 c. In the fuse unit F2,the anode 200′ may be close to the gate 400, and the cathode 100′ may beapart from the gate 400. The fuse device may further include a sidewallinsulation layer 10′ on sidewalls of the gate 400. One of the fuse unitF2 and the third conductive region 300 c may be a source, and the othermay be a drain. Therefore, the fuse unit F2, the third conductive region300 c, and the gate 400 may form a transistor T2.

Referring to FIG. 3B, the gate 400 may have a structure similar to thatof the fuse link 150 shown in FIG. 1B. The gate may include aninsulation layer 400 a and a conductive layer 400 b, which are formed ona substrate 1 in sequence, and the conductive layer 400 b may have amulti-layer structure. For example, the conductive layer 400 b may havea stacked layer structure in which a lower layer L1′ and an upper layerL2′ are stacked, wherein the lower layer L1′ and the upper layer L2′ maybe a poly-silicon layer and a silicide layer, respectively. However, thestructure and material of the conductive layer 400 b may vary. Forexample, the conductive layer 400 b may have either a single metal layerstructure or a multi-metal layer structure. If the conductive layer 400b has a bi-metal layer structure, the lower layer L1′ may be formed ofone of Ti, TiN, and TaN, for example, and the upper layer L2′ may beformed of one of W, Al, and Cu, for example. The list is not exhaustive.

The third conductive layer 300 c may include a third doped region 300 c′disposed in the substrate 1, and may further include a third contactlayer region 300 c″ on the top surface of the third doped region 300 c′.The third contact layer region 300 c″ may be a silicide region, forexample. The fuse unit F2 may have a stacked layer structure similar tothat of the third conductive region 300 c. The fuse unit F2 may includea fourth doped region F2′, which is disposed in the substrate 1, and afourth contact layer region F2″, which is disposed on the top surface ofthe fourth doped region F2′. Electrical resistance of the fourth contactlayer region F2″ may be lower than that of the fourth doped region F2′.Although the fourth contact layer region F2″ may be a silicide region,the material forming the fourth contact layer region F2″ may vary.

The fuse device shown in FIG. 3A may be changed as shown in FIG. 4A by aprogramming operation. In other words, FIG. 3A shows the fuse devicebefore the fuse device may be programmed, and FIG. 4A shows the fusedevice after the fuse device may be programmed. FIG. 4B is across-sectional view of the fuse device obtained along a line II-II′ ofFIG. 4A.

As shown in FIG. 4A, the fourth contact layer region F2″ in the fuselink 150′ may be blown due to a programming current applied from theanode 200′ to the cathode 100′. In FIGS. 4A and 4B, a referencecharacter B2 may refer to the blown region. Accordingly, as a portion ofthe fuse link 150′ is blown, a drain current of the transistor T2 maychange. The drain current can be measured by supplying a source voltageVs to one of the fuse unit F2 and the third conductive region 300 c,supplying a drain voltage Vd to the other, and supplying a gate voltageVg to the gate 400. The source voltage Vs or the drain voltage Vd may beapplied to the cathode 100′ or the anode 200′ of the fuse unit F2. Thedrain current of the transistor T2 when the fuse link 150′ is not blownand the drain current when the fuse link 150′ is partially blown may bedifferent, and thus the difference between the drain currents can bemeasured easily. To be more specific, when the fuse link 150′ ispartially blown as shown in FIG. 4A, it may be difficult to generate achannel between the fuse unit F2 and the third conductive region 300 c,and thus drain current may decrease significantly. When the fuse unit F2is used as a source, a change in the drain current due to the blowing ofthe fuse link 150′ may be very significant. In other words, when thefuse unit F2 is used as a source, a source resistance may change as thefuse link 150′ is blown. The change of the source resistance may inducechanges in gate voltage, drain voltage, and body bias. As a result, thechange in the source resistance may cause a significant change in thedrain current. A principle regarding changes in gate voltage, drainvoltage, and body bias due to a change in the source resistance of aconventional transistor is described in “Fundamentals of Modern VLSIdevices” (Taur and Ning).

At least one of the first and second conductive regions 300 a and 300 bshown in FIG. 1A may be modified to have a structure similar to that ofthe fuse unit F2 shown in FIG. 3A. An embodiment in which the first andsecond conductive regions 300 a and 300 b in FIG. 1A may be modified tohave the structure similar to the structure of the fuse unit F2 shown inFIG. 3A is shown in FIG. 5. Hereinafter, in the description of FIG. 5,the cathode 100, the fuse link 150, and the anode 200 will be referredas a first cathode 100, a first fuse link 150, and a first anode 200,respectively. Furthermore, the cathode 100′, the fuse link 150′, and theanode 200′ will be referred to as a second cathode 100′, a second fuselink 150′, and a second anode 200′.

Referring to FIG. 5, fourth and fifth conductive regions 500 a and 500 bare disposed at each of the two sides of the first fuse link 150. Thefourth and fifth conductive regions 500 a and 500 b may have fusestructures. The fourth conductive region 500 a may include the secondcathode 100′ and the second anode 200′ located apart from each other andthe second fuse link 150′ disposed between the second cathode 100′ andthe second anode 200′. Similarly, the fifth conductive region 500 b mayinclude a third cathode 100″ and a third anode 200″ located apart fromeach other and a third fuse link 150″ disposed therebetween. The fourthand fifth conductive regions 500 a and 500 b may be symmetrical withrespect to the lengthwise direction of first fuse link 150. However, itshould be understood that the shapes of the fourth and fifth conductiveregions 500 a and 500 b may vary and, therefore, do not need to besymmetrical. One of the fourth and fifth conductive regions 500 a and500 b may be a source, the other may be a drain, and the first fuse link150 between the fourth and fifth conductive regions 500 a and 500 b maybe a gate. Therefore, the fourth and fifth conductive regions 500 a and500 b and the first fuse link 150 may form a transistor T3.

In the structure shown in FIG. 5, a drain current of the transistor T3changes as one or more of the first through third fuse links 150, 150′,and 150″ may be blown by the programming current. FIG. 6 shows a fusedevice in which all of the first through third fuse links 150, 150′, and150″ may be blown. In FIG. 6, reference characters B1 through B3 mayindicate blown regions. If two or all of the first through third fuselinks 150, 150′, and 150″ are blown, a change in the drain current maybe more significant compared to the fuse devices shown in FIG. 1A orFIG. 3A.

According to at least one other example embodiment, a programming methodother than blowing can be used. More specifically, highly-resistantregions having a relatively high electrical resistance may be disposedin regions of the fuse links 150, 150′, and 150″. Therefore, the fusedevices may be programmed by changing positions of the highly-resistantregions.

FIGS. 7A, 9A, and 11 are plan views of fuse devices according to otherexample embodiments, wherein the fuse devices may be similar to the fusedevices shown in FIGS. 1A, 3A, and 5, respectively, except that the fuselinks 150, 150′, and 150″ may include highly-resistant regions R1, R2,and R3, respectively. FIGS. 7B and 9B are cross-sectional views obtainedalong lines III-III′ of FIG. 7A and of FIG. 9A, respectively. FIGS. 7A,7B, 9A, 9B, and 11 show example embodiments of fuse devices before thefuse devices may be programmed, and FIGS. 8A, 8B, 10A, 10B, and 12 showthe fuse devices after the fuse devices may be programmed.

Referring to FIGS. 7A and 7B, the upper layer L2 of the fuse link 150may include the highly-resistant region R1 and a remaining region RR1.The highly-resistant region R1 may have an electrical resistance higherthan the remaining region RR1 of the upper layer L2. For example, thehighly-resistant region R1 may be a poly-silicon region, and theremaining region RR1 of the upper layer L2 may be silicide regions. Thelower layer L1 may be a poly-silicon layer and thus, thehighly-resistant region R1 and the lower layer L1 may be formed of thesame material. However, example embodiments are not limited thereto. Ifthe conductive layer 150 b of the fuse link 150 has either a singlemetal layer structure or a multi metal layer structure, thehighly-resistant region R1 may be formed by partially doping nitrogen,oxygen, or resistive metal ions into the metal layer structure. Thehighly-resistant region R1 may be closer to the cathode 100 than to theanode 200, so that the highly-resistant region R1 may be moved to thecathode 100 easily. In FIG. 7A, a reference character F1′ may indicate afuse unit, and a reference character T1′ may indicate a transistor.

The highly-resistant region R1 may be moved into the cathode 100 byapplying a programming current to the fuse device shown in FIGS. 7A and7B. The highly-resistant region R1 may be moved due to a generalelectromigration (EM) effect. FIGS. 8A and 8B show a case in which thehighly-resistant region R1 may be moved into the cathode 100. When thehighly-resistant region R1 is moved from the fuse link 150 into thecathode 100, the electrical resistance of the fuse unit F1′ may change.In other words, the electrical resistance of the fuse unit F1′ may belower when the highly-resistant region R1 is located in the cathode 100compared to when the highly-resistant region R1 is located in the fuselink 150. The width of the cathode 100 may be greater than that of thefuse link 150. Accordingly, the electrical resistance of the fuse unitF1′ may change according to the movement of the highly-resistant regionR1. As a result, the drain current of the transistor T1′ may change. Amethod of measuring the drain current may be similar to the methoddescribed in reference to FIG. 2A.

Referring to FIGS. 9A and 9B, the fourth contact layer region F2″ of thesecond fuse link 150′ may include the highly-resistant region R2. Thehighly-resistant region R2 may have an electrical resistance higher thanremaining regions RR2 of the fourth contact layer region F2″. Forexample, the highly-resistant region R2 may be a poly-silicon region andthe remaining region RR2 of the fourth contact layer region F2″ may be asilicide region. However, the example embodiments are not limitedthereto, and the structure and material of the second fuse link 150′ mayvary. If the second fuse link 150′ has either a single metal layerstructure or a multi-metal layer structure, the highly-resistant regionR2 may be formed by partially doping nitrogen, oxygen, or resistivemetal ions into the metal layer structure. The highly-resistant regionR2 may be closer to the second cathode 100′ than to the second anode200′. In FIG. 9A, a reference character F2′ may indicate a fuse unit,and a reference number T2′ may indicate a transistor.

The highly-resistant region R2 may be moved into the second cathode 100′by applying a programming current to the fuse device shown in FIGS. 9Aand 9B. FIGS. 10A and 10B show the fuse device after the fuse device maybe programmed. When the highly-resistant region R2 is moved from thesecond fuse link 150′ into the second cathode 100′, the electricalresistance of the fuse unit F2′ and the drain current of the transistorT2′ may change. When the drain current is being measured, one of thefuse unit F2′ and the third doped region 300 c may be used as a source,and the other may be used as a drain. A method of measuring the draincurrent may be similar to the method described in reference to FIG. 4A.

Referring to FIG. 11, the first through third fuse links 150, 150′, and150″ may include the highly-resistant regions R1, R2, and R3,respectively. At least one of the highly-resistant regions R1 through R3may be moved into the first through third cathodes 100, 100′, and 100″,respectively. A possible result of moving the first through thirdhighly-resistant regions R1 through R3 into the first through thirdcathodes 100, 100′, and 100″, respectively, may be shown in FIG. 12.

The fuse devices according to example embodiments may be arranged in atwo-dimensional array structure, and may be applied to semiconductormemory devices, logic devices, microprocessors, field programmable gatearrays, one time programmable (OTP) devices, and other very large scaleintegration (VLSI) circuits for various purposes.

Additionally, methods of manufacturing a fuse device according toexample embodiments are briefly described below.

FIGS. 13A through 13C show a method of manufacturing a fuse deviceaccording to an example embodiment. The example embodiment may be amethod of manufacturing the fuse device of FIG. 1B.

Referring to FIG. 13A, after forming a stacked layer pattern, in whichan insulation layer 150 a and a lower layer L1 may be stacked insequence on a substrate 1, a sidewall insulation layer 10 may be formedon sidewalls of the insulation layer 150 a and the lower layer L1. Thesidewall insulation layer 10 may be formed by using an anisotropicetching method. After the sidewall insulation layer 10 is formed, firstand second doped regions 300 a′ and 300 b′ may be formed by dopingconductive impurities into the substrate 1 at both sides of theinsulation layer 150 a and the lower layer L1.

Referring to FIG. 13B, a metal layer 170 may be formed over thesubstrate 1 to cover the lower layer L1, the sidewall insulation layer10, and the first and second doped regions 300 a′ and 300 b′. Thesubstrate 1 may then be annealed so that a silicide reaction occursbetween the metal layer 170 and the lower layer L1 and between the metallayer 170 and first and second doped regions 300 a′ and 300 b′. Aportion of the metal layer 170 which does not react may be removedthereafter, as shown in FIG. 13C. FIG. 13C shows a structure similar tothat shown in FIG. 1B. In FIG. 13C, the upper layer L2 may be a resultof a reaction between the metal layer 170 and the lower layer L1, andthe first and second contact layer regions 300 a″ and 300 b″ may be aresult of the reaction between the metal layer 170 and the first andsecond doped regions 300 a′ and 300 b′.

The structure shown in FIG. 3B, which is similar to that shown in FIG.1B, may be manufactured by using a method similar to that described inreference to FIGS. 13A through 13C, and the structure shown in FIG. 5may also be manufactured by using the method described in reference toFIGS. 13A through 13C.

FIGS. 14A through 14C show a method of manufacturing a fuse deviceaccording to another example embodiment. The method illustrated in FIGS.14A through 14C may be used to manufacture the fuse device shown in FIG.7B.

Referring to FIG. 14A, the insulation layer 150 a and the lower layer L1may be formed on the substrate 1 in sequence.

Referring to FIG. 14B, a mask layer 160 may be formed on apre-determined region of the lower layer L1. The mask layer 160 may bean insulation layer such as a silicon-nitride layer or a silicon-oxidelayer, but is not limited thereto. A metal layer 170 may be formed onthe lower layer L1 to cover the mask layer 160. The substrate 1 may beannealed so that a silicide reaction occurs between the lower layer L1and the metal layer 170. Thereafter, a portion of metal layers 170 whichdid not react and the mask layer 160 may be removed, as shown in FIG.14C.

In FIG. 14C, the upper layer L2 may be a result of a reaction betweenthe lower layer L1 and the metal layer 170. While the substrate 1 isannealed, a portion of the lower layer L1 covered by the mask layer 160(FIG. 14B) may not react with the metal layer 170, and thus the portionof the lower layer L1 may not be silicided. The portion of the lowerlayer L1 that is not silicided may be the highly-resistant region R1.

Accordingly, the fuse device shown in FIGS. 7A and 7B may bemanufactured by using the method described in reference to FIGS. 14Athrough 14C. Also, the highly-resistant region R2 shown in FIGS. 9A and9B may be formed by using a method similar to the method of forming thehighly-resistant region R1 shown in FIG. 14C. The fuse device shown inFIGS. 9A and 9B may be manufactured by using a method similar to thatdescribed in reference to FIGS. 14A through 14C. Since the structureshown in FIG. 11 is similar to a combination of structures shown inFIGS. 7A and 9A, the structure shown in FIG. 11 may also be formed byusing a method similar to that described in reference to FIGS. 14Athrough 14C.

Meanwhile, when the conductive layer 150 b shown in FIG. 7B has either asingle metal layer structure or a multi metal layer structure, ahighly-resistant region may be formed by partially doping nitrogen,oxygen, or resistant metal ions into the conductive layer 150 b. Themethod may also be used when the highly-resistant regions R1 through R3shown in FIGS. 9B and 11 are formed.

While the example embodiments have been particularly shown and describedwith reference to example embodiments, it will be understood by those ofordinary skill in the art that various changes in form and details ofthe fuse devices shown in FIGS. 1A through 12 may be made thereinwithout departing from the spirit and scope of the example embodimentsas defined by the following claims. It should be understood that variouschanges may be made in the shapes of the cathodes 100, 100′, and 100″,the anodes 200, 200′, and 200″, and the fuse links 150, 150′, and 150″.Furthermore, a bulk silicon substrate, a silicon on insulator (SOI)substrate, and other types of substrates may be used as the substrate 1,for example.

1. A method of operating a fuse device comprising a fuse unit which includes a cathode, an anode, and a fuse link connecting the cathode and the anode, and a transistor including at least a first portion of the fuse unit, the method comprising: applying a programming current to the fuse unit; and measuring a drain current of the transistor.
 2. The method of claim 1, wherein the fuse link is a gate of the transistor.
 3. The method of claim 2, wherein the transistor further comprises a source and a drain disposed on a substrate at an each side of the fuse link.
 4. The method of claim 3, wherein at least one of the source and the drain has a fuse structure comprising: two regions located apart from each other; and a link region which has a width less than that of each of the two regions and is located between the two regions.
 5. The method of claim 4, further comprising: applying another programming current to at least one of the source and the drain having the fuse structure, prior to the measuring of the drain current.
 6. The method of claim 3, wherein measuring the drain current includes supplying a gate voltage to at least one of the cathode and anode, and supplying a voltage between the source and the drain.
 7. The method of claim 1, wherein the transistor comprises: the fuse unit as a source; a drain located apart from the source; and a gate disposed on a substrate between the source and the drain.
 8. The method of claim 7 wherein measuring the drain current includes supplying a gate voltage to the gate, and supplying a voltage between the cathode and the drain.
 9. The method of claim 1, wherein the transistor comprises: the fuse unit as a drain; a source located apart from the drain; and a gate disposed on a substrate between the source and the drain.
 10. The method of claim 9, wherein measuring the drain current includes supplying a gate voltage to the gate, and supplying a voltage between the cathode and the source.
 11. The method of claim 1, wherein applying the programming current includes blowing the fuse link.
 12. The method of claim 1, wherein the fuse link comprises: a conductive layer; and a highly-resistant region in a portion of the conductive layer, wherein the highly-resistant region is a region having an electrical resistance higher than that of a remaining portion of the conductive layer.
 13. The method of claim 12, wherein applying the programming current includes, moving the highly-resistant region into the cathode. 